update docs.uchiwa.io links to use new paths on docs.sensu.io

[cwjohnston]

Description

Update links in the README.md to reflect new documentation site

Related Issue

Closes #790

Motivation and Context

We merged the Uchiwa documentation into the sensu-docs project, which broke these links. It is good to fix broken links.

How Has This Been Tested?

Markdown preview looks good.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov-io]

Codecov Report

Merging #792 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #792   +/-   ##
=======================================
  Coverage   21.49%   21.49%           
=======================================
  Files          28       28           
  Lines        2466     2466           
=======================================
  Hits          530      530           
  Misses       1871     1871           
  Partials       65       65

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[palourde]

👍